A Privacy-Preserving Framework Using Homomorphic Encryption for Smart Metering Systems

. 2023 May 14;23(10):4746. doi: 10.3390/s23104746

Algorithm 5 Variance algorithm for ciphertexts.

1:
Input N: the number of the household
2:
Input $r o w C o u n t$ : the count of records per day of each household
3:
Input $c i p h e r t e x t s$ : the ciphertexts array transferred from the service provider
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Input $e v a l u a t o r$ : the object that performs homomorphic computations
5:
for $i n d e x = 1, 2, \dots, N$ do
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$c \leftarrow c i p h e r t e x t s [i n d e x]$
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$c_{c o p y} \leftarrow c o p y (c)$
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$e v a l u a t o r . s u m E a c h E l e m e n t (c)$
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$c . a v e r a g e B y (r o w C o u n t)$
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$c \leftarrow e v a l u a t o r . M u l t i p l y (c, - 1)$
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$c \leftarrow e v a l u a t o r . A d d (c, c_{c o p y})$
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$c^{'} \leftarrow e v a l u a t o r . M u l t i p l y (c, c)$
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$e v a l u a t o r . s u m E a c h E l e m e n t (c^{'})$
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$c^{'} . a v e r a g e B y (r o w C o u n t)$
15:
end for
16:
Output $c i p h e r t e x t s$ array back to the service provider